Ethylenically unsaturated polyesters

ABSTRACT

Ethylenically unsaturated polyesters are provided. These ethylenically unsaturated polyesters are the reaction product of (a) a polyhydroxy polyester material that is the reaction product of at least one organic dicarboxylic acid, at least one diepoxide, and, optionally, monocarboxylic acid and/or monoepoxide with (b) a polymerizable ethylenically unsaturated compound having a functional group reactive with the hydroxyl groups of the polyhydroxy polyester. This product is particularly useful as a protective coating material.

This invention relates to ethylenically unsaturated polyesters and toradiation polymerizable compositions prepared therefrom. This invention,in another aspect, relates to radiation-polymerized polyester coatingsand substrates prepared with such coatings.

Protective coatings for various substrates, such as plastic, wood, andmetal, are well-known and a wide variety of different coatingcompositions have been proposed in the past for such use. Someprotective coatings serve a number of different purposes such asproviding abrasion and scratch resistance and protection against waterspotting and solvent damage. Two important types of protective coatingsare lacquer-type or reactive-type coatings.

The lacquer-type coating compositions are provided as a solvent solutionof naturally occurring resins or synthetic solid resins. Thelacquer-type coating is obtained by coating a substrate with thesolution and allowing the solvent to evaporate. The resulting driedcoating may, in many examples, be sanded to smooth the surface andcorrect defects and polished to enhance surface gloss. The coating, eventhough it may be somewhat abrasion resistant, is still soluble incertain solvents and therefore is readily damaged by solvent.

The reactive-type protective coating compositions contain one or morecompounds which contain functional groups, such as ethylenicallyunsaturated groups, epoxy groups, and isocyanate groups, that react tochain-extend and usually crosslink the compound and form a solidcoating. The reaction forming the solid coating can take days, evenweeks before the coating becomes hard enough to be handled and shippedwithout imprinting from adjacent surfaces.

One class of reactive-type coatings are the ethylenically unsaturatedpolyesters which can be polymerized under the influence of activatingenergy. For example, Fekete et al. (U.S. Pat. No. 3,256,226) describehydroxy polyether polyesters having terminal ethylenic unsaturationwhich are the reaction product of dicarboxylic acids, ethylenicallyunsaturated monocarboxylic acids, and diepoxide compounds. Radlowe et al(U.S. Pat. No. 3,847,770) describe betahydroxy polyitaconates that arethe reaction product of itaconic acid and polyepoxides and which can becopolymerized with polyacrylates. Fekete et al. and Radlowe et al.,however, do not teach how to use their reaction product to preparepolyesters that have a sufficient number of ethylenically unsaturatedgroups to be polymerizable to highly abrasive resistant coating.Wendling (U.S. Pat. No. 4,309,529 and No. 4,316,952) does discloseadducts of diepoxide and itaconic acid that do have a sufficient numberof ethylenically unsaturated groups to be polymerizable to highlyabrasion resistant coatings but because of the hydrophilic nature of thediepoxide that is used, namely a bisepoxy heterocyclic compound, thecoatings obtained tend to be hydrophilic and subject to damage byaqueous substances. Various major coating resins, including polyestercoating resins, are described in Useful Facts and Figures, 3rd Ed.,Technical Publication No. MSB-111-38, Reliance Universal, Inc.,Louisville, Ky., pp. 15-18.

Another class of reactive coatings are the urethane polyethers which canbe polymerized by actinic radiation and/or chemical initiation. Forexample, Tefertiller et al. (U.S. Pat. No. 4,233,425) describe additionpolymerizable polyethers having a polyether backbone and at least onependant ethylenically unsaturated aliphatic urethane group, such as thereaction product of a polyether polyol and 2-isocyanatoethylmethacrylate. These coatings may be subject to damage by extendedcontact with some solvents. Dow Chemical Company product bulletin"Developmental Monomer XAS-10743.00, Isocyanatoethyl Methacrylate,C.A.S. Number 030674-80-7" further describes isocyanatoethylmethacrylate.

In accordance with the invention, ethylenically unsaturated polyestersare provided which, under the influence of activating energy, such asultraviolet radiation, polymerize to materials which as coatings haveexcellent solvent resistance, heat resistance, and abrasion resistanceas shown hereinafter. Such polyesters are the reaction product of (a) apolyhydroxy polyester material that is the condensation or additionproduct of at least one organic dicarboxylic acid, at least one organicacyclic or carbocyclic diepoxide and, optionally, monocarboxylic acidand/or monoepoxide, and (b) a polymerizable ethylenically unsaturatedcompound having a functional group, such as isocyanato (--NCO), reactivewith hydroxyl groups of the polyester material (a). The ethylenicallyunsaturated polyesters can be oligomers which have a number averagemolecular weight of 500 to 30,000, preferably 1000 to 30,000. Theethylenically unsaturated polyesters of the invention have an ethylenicunsaturation equivalent weight of less than about 330, such ethylenicunsaturation generally being alpha, beta ethylenic unsaturation.

Further provided are coating compositions comprising the above-describedethylenically unsaturated polyester and an amount of a polymerizationcatalyst sufficient to effectively polymerize the ethylenicallyunsaturated polyester. There is also provided a process for providing asubstrate with a protective coating that is resistant to solvents andabrasion comprising the steps of coating the substrate with a coatingcomposition comprising the ethylenically unsaturated polyester describedabove and a polymerization catalyst, and curing the applied coating byexposure of the coating to suitable energy.

The ethylenically unsaturated polyesters of the invention are useful,for example, in coatings, adhesives, caulking and sealing compositions,casting and molding compositions, impregnating compositions and binders.These ethylenically unsaturated polyesters are particularly useful inprotective coatings because of their excellent abrasion resistance, heatresistance, and solvent resistance.

A class of ethylenically unsaturated polyesters of the invention arethose represented by the formula ##STR1## wherein each R¹ and R² isindependently a divalent organic group having 2 to 40 carbon atomsselected from saturated or unsaturated straight or branched aliphatic orcycloaliphatic groups or aromatic groups, the R¹ containing noheterocyclic groups, i.e., R¹ is acyclic or carbocyclic;

each R³ is independently hydrogen or an alkylene group having 2 or 3catenary carbon atoms that together with atoms in R¹ and the --CH--CH--group to which it is bonded form a 5- or 6-membered trivalentcycloalkane group; ##STR2## in which R is hydrogen or a methyl group;

R⁷ is a monovalent organic radical having 1 to 24 carbon atoms and isselected from saturated or unsaturated straight or branched chainaliphatic groups and aromatic groups;

R⁸ is an alkylene group having 2 to 12 carbon atoms; and

R⁹ is a divalent organic group selected from linear, branched, andcyclic alkylene groups having 2 to 40 carbon atoms, phenylene groups,naphthylene groups, and phenylenemethylenephenylene groups, the organicgroup can be optionally substituted by up to four lower alkyl groupshaving 1 to 4 carbon atoms;

R¹⁰ is hydrogen or an alkyl group having 1 to 4 carbon atoms; and##STR3## where R¹, R³, and R⁴ are as defined above and R¹² is amonovalent organic radical having 1 to 20 carbon atoms and is selectedfrom saturated and unsaturated straight or branched chain aliphatic oraromatic groups;

R⁶ is selected from R¹¹ and ##STR4## where R¹, R³, R⁴, R⁷ and R¹¹ are asdefined above;

n is a number having an average value of 1 to 100, preferably n is about1 to 10, except that where ##STR5## then n is a number having an averagevalue of 0 to 100, preferably 0 to 10.

A preferred subclass of ethylenically unsaturated polyesters are thoserepresented by the formula ##STR6## where R¹, R², R³ and R⁷ are asdescribed above, each R⁴ is independently selected from hydrogen and##STR7## where R and R⁸ are as described above, and n is a number havingan average value of 1 to 100, preferably 1 to 10.

The compounds of this invention are generally prepared in two steps. Inthe first step, a polyhydroxy polyester, such as that having the formula##STR8## wherein R¹, R², R³, R⁷, and n are as defined for formula I, isprepared by the catalyzed, preferably chromic ion or tertiary aminecatalyzed, reaction of n moles of dicarboxylic acid, HOOCR² COOH, and 2moles of a monocarboxylic acid, HOOCR⁷, with n+1 moles of a diepoxide,##STR9##

In the second step, the polyhydroxy polyester of the first step isreacted with a polymerizable ethylenically unsaturated compound havingfunctional groups reactive with the hydroxyl groups of the hydroxypolyester.

The preparation of the ethylenically unsaturated polyester of thisinvention is illustrated in the following reaction schemes, where R, R¹through R⁹, and n are as defined above for general formula I. Scheme 1illustrates the preparation of a polyhydroxy polyester intermediate I'and scheme 2 shows the preparation of an ethylenically unsaturatedpolyester of general formula I. Scheme 3 illustrates the preparation ofa polyhydroxy polyester intermediate II', and schemes 4, 5 and 6 showthe preparation of various examples of the ethylenically unsaturatedpolyester II from polyhydroxy polyester II' by reaction withhydroxyl-reactive, unsaturated compounds.

Scheme 1 ##STR10## Scheme 2 ##STR11## Scheme 3 ##STR12## In the aboveschemes and formulas I and II, the oxirane rings of the diepoxide areshown as opening with the oxygen atom attached to the beta carbon.However, some oxirane rings may open such that the oxygen is attached atthe alpha carbon. Scheme 4 ##STR13## Scheme 5 ##STR14## Scheme 6##STR15##

In the first step, the reaction generally can be performed in thepresence of a solvent for the reactants and an inhibitor for thermalpolymerization of ethylenically unsaturated group-containing compoundsby heating the reaction mixture at a temperature from 50° C. to 150° C.,preferably about 70° C. to 100° C. Heating for 2 to 40 hours usuallysuffices to complete the reaction.

Diepoxides, ##STR16## where R¹ and R³ are as defined for formula I, thatcan be used in preparing the compounds of the invention are branched orstraight chain aliphatic, cycloaliphatic, or aromatic compounds havingtwo oxirane groups and a molecular weight of up to about 1000. Thedivalent organic radical, R¹, can be substituted with non-interferringgroups and can contain catenary --O--, ##STR17## or SO₂, provided noheterocyclic groups are present. The term "no heterocyclic groups" meansthose cyclic groups which are present are carbocyclic, that is, theyhave only carbon atoms in the ring structure, usually 5 or 6, e.g.,##STR18## Particularly useful are the glycidyl ethers of dihydricalcohols. Included among the diepoxides that can be used are thediglycidyl ether of bisphenol A, poly(glycidyl bisphenol),3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate,3,4-epoxy-6-methylcyclohexylmethyl3,4-epoxy-6-methylcyclohexanecarboxylate,bis(3,4-epoxy-6-methylcyclohexylmethyl)adipate, dipentene oxide,1,4-butanediol diglycidyl ether, and resorcinol diglycidyl ether.Particularly preferred is the diglycidyl ether of bisphenol A, ##STR19##

Commercially available diepoxides that can be used include diglycidylether of bisphenol A (e.g., Epon™ 828, Shell Chemical Co., and DER™ 332,Dow Chemical Co.), poly(glycidyl bisphenol) (e.g. Epon# 1002, ShellChemical Co.) vinylcyclohexene dioxide (e.g., ERL™-4206, Union CarbideCorp.), 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (e.g.,ERL™-4221, Union Carbide Corp.) 3,4-epoxy-6-methylcyclohexylmethyl3,4-epoxy-6-methylcyclohexanecarboxylate (e.g., ERL™-4201, Union CarbideCorp.), bis(3,4-epoxy-6-methylcyclohexylmethyl)adipate (e.g., ERL™-4289,Union Carbide Corp.), aliphatic epoxy modified with polypropylene glycol(e.g., ERL™-4050 and ERL™-4052, Union Carbide Corp.), dipentene dioxide(e.g., ERL™-4269, Union Carbide Corp, and Oxiron™ 2001, FMC Corp.), and1,4-butanediol diglycidyl ether (e.g., Araldite™ RD-2, Ciba-Geigy).

Dicarboxylic acids that can be used in the practice of this inventioncan be represented by the formula ##STR20## where R² is as defined forformula I. The dicarboxylic acids can be saturated or unsaturated,aliphatic, cycloaliphatic, or aromatic, and can be substitutedoptionally by non-interfering groups such as saturated alkyl,unsaturated alkyl, sulfonate, ester, ether, halohydrocarbon, amide, andcarbamate. Examples of suitable dicarboxylic acids include: succinic,glutaric, adipic, suberic, sebacic, undecanedicarboxylic,hexadecanedicarboxylic, dimerized fatty acids (such as obtained by thedimerization of olefinically unsaturated monocarboxylic acids containing16 to 20 carbon atoms such as oleic acid, linoleic acid and the like).Other useful dicarboxylic acids are diglycolic, dilactic,3,3'-(ethylenedioxy)dipropionic, phthalic, isophthalic, terephthalic,5-sulfonatoisophthalic, diphenic, maleic, fumaric, itaconic,phenylenediacetic, benzylsuccinic, 1,4-naphthalenedicarboxylic,5-chloro-1,3-benzenedicarboxylic, tetrachlorophthalic,1,2-cyclohexanedicarboxylic, 2,4-pyridinedicarboxylic,2,5-tetrahydrofuranedicarboxylic, 1,5-pent-2-enedioic,2-methyleneglutaric, 2-methyleneadipic, 3-methylitaconic,3,3-dimethylitaconic and mixtures thereof. The preferred dicarboxylicacids are the alpha methylene dicarboxylic acids, particularly itaconicacid.

Monocarboxylic acids that can be optionally used in the practice of thisinvention have the formula ##STR21## where R⁷ is as defined for formulaI. The monocarboxylic acids may be saturated or unsaturated, aliphatic,cycloaliphatic, or aromatic and may be substituted by non-interferinggroups such as saturated alkyl, unsaturated alkyl, heterocyclic,sulfonate, ester, ether, halohydrocarbon, amide and carbamate. Examplesof such monocarboxylic acids include: acetic, propionic, butanoic,valeric, hexanoic, octanoic, undecanoic, hexadecanoic, tetracosanoic,acrylic, methacrylic, crotonic, 2-butenoic, 3-hexenoic, undecylenic,oleic, nervonic, benzoic, phenylacetic, 4-chlorobenzoic,4-trifluoromethylbenzoic and 4-methoxycarbonylbenzoic acid. Preferredmonoacids are the alpha,beta-unsaturated carboxylic acids, particularlyacrylic and methacrylic.

Monoepoxides that can be optionally used in the pratice of thisinvention have the formula ##STR22## wherein R¹² is as defined above.The monoepoxides can be saturated or unsaturated aliphatic,cycloaliphatic, or aromatic and can be substituted with noninterferinggroups and can contain catenary --O--, ##STR23## and --SO₂. Examplesinclude glycidyl ethers of monohydric alcohols, glycidyl esters ofmonocarboxylic acids or olefin monoepoxides, including the glycidylesters of acrylic and methacrylic acid, the glycidyl ether of butanol,and styrene oxide.

In the second step of the preparation of the ethylenically unsaturatedpolyester compositions of the invention, the polyhydroxy polyesterproduct of the first step is reacted with a sufficient amount of thepolymerizable ethylenically unsaturated compound having functionalgroups reactive with hydroxyl groups of the polyhydroxy polyester toprovide a polyester preferably having an equivalent weight of less thanabout 330 per polymerizable ethylenic group. Such functional groupsreactive with hydroxyl groups include carboxylic acid, carboxylic acidchloride, carboxylic acid anhydride, and isocyanate. Preferred of suchcompounds are acrylic, methacrylic, and crotonic acid, acrylic,methacrylic, and crotonic acid chloride, acrylic, methacrylic, crotonic,and maleic anhydride, N-methylolacrylamide, N-alkoxymethylacrylamide,and ethylenically unsaturated azlactones. Isocyanatoalkyl acrylates andmethacrylates and ethylenically unsaturated azlactones are morepreferred. Examples of the most preferred isocyanatoalkyl acrylates andmethacrylates are 2-isocyanatoethyl acrylate, 3-isocyanatopropylacrylate, 3-isocyanatopropyl methacrylate, and 2-isocyanatoethylmethacrylate. Also among the polymerizable ethylenically unsaturatedcompounds are the reaction product of one mole of hydroxyalkyl acrylateor methacrylate and one mole of a straight or branched aliphatic,cycloaliphatic, or aromatic or alkenylaromatic diisocyanate such as2-(4-isocyanatophenylaminocarbonyloxy)ethyl acrylate and methacrylate,2-(3-isocyanato-4-methylphenylaminocarbonyloxy)ethyl acrylate,2-(5-isocyanato-1,3,3-trimethylcyclohexylmethylaminocarbonyloxy)ethylacrylate and methacrylate,2-(1-methyl-1-(4-(1-methyl-1-isocyanatoethyl)phenyl)ethylaminocarbonyloxy)ethylacrylate or methacrylate,2-(1-methyl-1-(3-(1-methyl-1-isocyanatoethyl)phenyl)ethylaminocarbonyloxy)ethylacrylate or methacrylate, and 2-(6-isocyanatohexylaminocarbonyloxy)ethylacrylate and methacrylate which are the reaction product of 1,4-benzenediisocyanate, 2,4-toluene diisocyanate,5-isocyanato-1,3,3-trimethylcyclohexylmethyl isocyanate,1,4-bis(1-methyl-1-isocyanatoethyl)benzene,1,3-bis-(1-methyl-1-isocyanatoethyl)benzene and 1,6-hexane diisocyanatewith 2-hydroxy-ethyl acrylate and methacrylate, respectively. Examplesof the preferred ethylenically unsaturated azlactones are2-ethenyl-1,3-oxazoline-5-one,2-ethenyl-4,4-dimethyl-1,3-oxazolin-5-one,2-isopropenyl-4,4-dimethyl-1,3-oxazolin-5-one, and2-isopropenyl-4-methyl-4-dodecyl-1,3-oxazolin- 5-one.

Optionally, the polyhydroxy polyester can be reacted with anon-ethylenically unsaturated compound having a functional groupreactive with the hydroxyl group of the polyhydroxy polyester. Thisfurther substitution can alter the solubility or compatibility of theunsaturated polyester. Examples of non-ethylenically unsaturatedcompounds include isocyanates such as butyl isocyanate, octadecylisocyanate, phenyl isocyanates, acid halides and anhydrides such asbenzoyl chloride, oleylchloride, butyryl anhydride, succinic anhydride,and para-toluene sulfonyl chloride.

Since the ethylenically unsaturated polyester composition is preferablyused as a coating composition, the solvents used in the first step, inwhich the polyhydroxy polyester is prepared, preferably have a boilingpoint at atmospheric pressure of less than about 200° C. so that thesolvents are readily volatilized from a coating of the composition, andhave a boiling point of at least 50° C. so that the temperature at whichthe polyhydroxy polyester and the ethylenically unsaturated polyesterare prepared can be at least 50° C. without the use of pressureequipment. The preparation reactions can be carried out in pressureequipment, if desired, under pressures of several atmospheres or more.Most solvents having an atmospheric boiling point within the range of50° to 200° C. can be used provided they do not have interfering groups,e.g., carboxylic acid groups, which would interfere by reaction with anepoxy group, or hydroxyl groups which would interfere during the secondstep of the reaction. It is preferred that solvents be selected fromesters, ketones, or aromatic hydrocarbons such as butyl acetate,cellosolve acetate, methyl isobutyl ketone, and xylene. Generally, inthe first step of the reaction, the amount of solvent results in asolution containing up to 100 percent solids, preferably about 50 to 80percent solids, the higher solids contents used where the molecularweight of the resulting polyhydroxy polyester is low, and in the secondstep, the amount of solvent results in a solution containing up to about80 percent reactive material, preferably about 50 to 70 percent reactivematerial.

Use of thermal inhibitors in compositions containing ethylenicallyunsaturated groups is well known and such inhibitors are used in amountsup to about 0.02 percent by weight of the composition exclusive ofsolvents. Examples of useful thermal inhibitors are quinone,naphthoquinone, hindered phenols, and hydroquinone monoalkyl ethers.Generally, there is present in the commercially obtained ethylenicallyunsaturated compounds sufficient inhibitor to prevent thermalpolymerization during synthesis.

The ethylenically unsaturated polyesters of the invention that have beenprepared to have an equivalent weight of less than about 330 perethylenic group present in the dicarboxylic acid groups R², the terminalgroups R⁵ and R⁶, and the pendant groups R⁴, are responsive topolymerization even in the presence of oxygen when subjected to heat oractinic radiation in the presence of a source of free radicals. Withequivalent weight per ethylenic group increasing above 330,polymerization proceeds more and more slowly and the resistance toscratching of a substrate coated with the polymerized product becomesincreasingly reduced.

The radiation polymerizable compositions of the invention contain apolyester backbone with pendant groups having polymerizable ethylenicunsaturation. The compositions also preferably contain sufficientpolymerization initiators for bringing about polymerization on exposureof the composition to actinic radiation.

Polymerization initiators suitable for use in the crosslinkablecompositions of the invention are those compounds which liberate orgenerate a free-radical on addition of energy. Such catalysts includeperoxy, azo, and redox systems all of which are well known and aredescribed frequently in polymerization art. Included among free-radicalcatalysts are the conventional heat-activated catalysts such as organicperoxides and organic hydroperoxides, e.g., benzoyl peroxide,tertiary-butyl perbenzoate, cumene hydroperoxide,azobis(isobutyronitrile) and the like. The preferred catalysts arephotopolymerization initiators which facilitate polymerization when thecomposition is irradiated. Included among such initiators are acyloinand derivatives thereof, such as benzoin, benzoin methyl ether, benzoinethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, andmethylbenzoin, diketones such as benzil and diacetyl etc.: phenones suchas acetophenone, 2,2,2-tribromo-1-phenylethanone,2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone,2,2,2-tribromo-1-(2-nitrophenyl)ethanone, benzophenone, and4,4'-bis(dimethylamino)benzophenone. Normally, the initiator is used inamounts ranging from about 0.01 to 10% by weight of the totalpolymerization composition. When the quantity is less than 0.01% byweight, the polymerization rate becomes extremely low. If the initiatoris used in excess of 5% by weight, no correpondingly improved effect canbe expected. Thus addition of such greater quantity is economicallyunjustified. Preferably, about 0.25 to 4.0% of initiator is used in thepolymerizable composition.

The polyester compositions of the invention can optionally be blendedwith ethylenically unsaturated materials to modify or enhance theproperties of the polyester, e.g., hardness, flexibility, and adhesion.Such materials may also be used as reactive diluents. Ethylenicallyunsaturated monomers suitable for formulations with the polyestersinclude methyl methacrylate, ethyl acrylate, 2-ethylhexyl acrylate,chlorohexyl acrylate, styrene, 2-chlorostyrene, 2,4-dichlorostyrene,acrylic acid, acrylamide, acrylonitrile, t-butyl acrylate, methylacrylate, butyl acrylate, 2-(N-butylcarbamyl)ethyl methacrylate and2-(N-ethylcarbamyl)ethyl methacrylate. Other modifying monomers that canbe incorporated into the composition of the invention include1,4-butylene dimethacrylate or diacrylate, ethylene dimethacrylate,hexanediol diacrylate or dimethacrylate, glyceryl diacrylate ordimethacrylate, glyceryl triacrylate or trimethacrylate, pentaerythritoltriacrylate or trimethacrylate, pentaerythritol tetraacrylate ortetramethacrylate, diallyl phthalate, dipentaerythritol pentaacrylate,neopentylglycol diacrylate, and1,3,5-tri(2-methacryloyloxyethyl)-s-triazine. In addition to thereactive monomers, other polymerizable ethylenically unsaturatedcoreactants can be blended with the polyesters of the invention. Suchcoreactants include acrylated epoxy, acrylated urethane, and acrylatedcellulose oligomers and resins. Generally, up to about one part ofmodifying materials per part by weight of ethylenically unsaturatedpolyester can be used. Also, small amounts of non-reactive film-formingresins, such as nitrocellulose, can be added.

The ethylenically unsaturated polyester compositions of the inventioncan also include variety of additives utilized for their known purpose,such as stabilizers, inhibitors, lubricants, flexibilizers, pigments,dyes, and fillers such as diatomaceous earth, metal oxides, fiberglass,glass bubbles, and talc. Fillers can generally be used in proportions upto about 200 percent by weight of the curable composition but preferablyare used up to about 50 percent by weight. Where the polymerizing energyis radiation, it is desirable that the additives be transparent to theradiation.

Coating compositions of the invention can be prepared by simply mixing(under "safe light" conditions if the composition is to be sensitized tovisible light) the ethylenically unsaturated polyesters of theinvention, with the polymerization catalyst and initiator (where used),and where used, the modifying monomers, binders and other additives.Where the polymerization catalyst is a photoinitiator, the compositioncan be used for in situ curing process because of the insensitivity tooxygen.

The ethylenically unsaturated polyesters of the invention can be used asadhesives, caulking and sealing compositions, casting and moldingcompositions, potting and encapsulating compositions, impregnatingcompositions, and binders. The photopolymerizable compositions areparticularly suitable for applications in the field of protectivecoatings, e.g., furniture finishes, and graphic arts, because of theirsuperior abrasion resistance, heat resistance, and adhesion to manyrigid, resilient and flexible substrates, such as metal, plastic,rubber, glass, paper, wood and ceramic. Their excellent resistance tomost solvents and chemicals and their capability for forming highresolution images provide further advantages in coatings and graphicarts. Among such uses are developable resists for chemical milling,gravure images, offset plates, stencil making, screenless lithography,relief printing plates, printed circuits, radiation-cured protectivecoatings for glass, metal surfaces and the like. Also, the polyesters ofthe invention are form-stable at room temperatures (they do not flow attemperatures below about 30° C.), and many are non-tacky at thesetemperatures.

The polymerization of photopolymerizable compositions of the inventionoccurs on exposure of the compositions to any source of radiationemitting actinic radiation at a wavelength within the ultraviolet andvisible spectral regions. Suitable sources of radiation include mercury,xenon, carbon arc and tungsten filament lamps, sunlight, etc. Exposuresmay be from less than about 1 second to 10 minutes or more, dependingupon the amounts of the particular polymerizable materials present, thephotopolymerization catalyst being utilized as well as the radiationsource, distance from the source, and the thickness of the coating to becured. The compositions may also be polymerized by exposure to electronbeam irradiation. Generally, the dosage is from less than 1 megarad to30 megarad or more. One of the major advantages using electron beamcuring is that highly pigmented compositions can be effectively cured ata faster rate than by mere exposure to actinic radiation.

Compositions of the invention that contain a thermally activatedpolymerization initiator are polymerized by heating the composition in asuitable mold or as a layer on a substrate to a temperature at which theinitiator is activated, generally from about 30° C. to 150° C. for froma few minutes to 24 hours or more, depending on the particular activatorused and its concentration.

The cured product of the invention is an insoluble or crosslinkedmaterial derived from the polyester by the free radical polymerizationof the ethylenically unsaturated groups of the polyester of theinvention.

The instant invention will be illustrated by referring to the followingspecific but nonlimiting examples.

In these examples, the following tests were used to evaluate thecoatings.

Abrasion Resistance: A sample of polyester film having a cured coatingof the ethylenically unsaturated polyester composition is abraded usinga Taber Abraser™ (available from Gardner Neotech Co.) equipped with CS17 wheels under a 500 gram load for 30 cycles. The haze value, aparameter inversely proportional to abrasion resistance, of the abradedsample is measured using a Gardner Hazemeter Model No. UX10 (availablefrom Gardner Neotech Co.). Haze values below about 6.5 are preferred.

Heat Resistance: Heat resistance is measured using a test referred to asthe "hot cup print test", a modification of the Boiling WaterResistantce Test (NEMA Standard LDI-202). A single layer of cheesecloth(8 cm×8 cm) wet with water is placed on a polyester film having a curedcoating of the ethylenically unsaturated polyester composition, an 800ml aluminum beaker containing 650 ml of boiling water is placed on thewet cheese cloth and allowed to stand for 20 minutes. The beaker andcheese cloth are removed, the film is wiped dry and inspected forprint-through from the cheese cloth.

Solvent Resistance: A cotton ball is saturated with the solvent beingtested and is placed on the surface of a polyester film having a curedcoating of the ethylenically unsaturated polyester composition. Thesolvent-saturated cotton ball is covered with a watch glass (or othercover) to retard solvent evaporation. The covered sample is allowed tostand at room temperature, with additional solvent added if necessary,to maintain wetness of the cotton ball. After time periods of 10minutes, 30 minutes, 60 minutes, and each hour thereafter for 6 hours,the cover and cotton ball are removed, the surface is wiped dry and thesample surface is visually inspected for any change in surfaceappearance.

EXAMPLE 1

A 2-liter, 3-necked flask equipped with a mechanical stirrer, dry airbubbler, and condenser with drying tube was charged with

350 g DER™ 332 (diglycidyl ether of bisphenol A having an epoxideequivalent weight of 175 available from Dow Chemical Co.), 1.0 mole;

97.6 g itaconic acid, 0.75 mole;

36.0 g acrylic acid, 0.5 mole;

322 g butyl acetate; and

1.0 ml Cordova Accelerator AMC-2 (an organic soluble chromium saltavailable from Cordova Chemical Company).

A flow of about 5 ml/min of dry air was established through the solutionand it was stirred for about 8 to 12 hours at 80° C. Progress of thereaction was monitored by withdrawal of 1 g. samples of solution thatwere titrated for residual epoxy and acid respectively. Heating of thesolution was continued until residual epoxide level fell to less than 3%and the acid level fell to less than 5% of the initial charge, at whichtime the solution was cooled to room temperature. A solution in butylacetate of a polyhydroxy polyester having a ratio of 4 moles diepoxide:3 moles itaconic acid: 2 moles acrylic acid was obtained.

To the polyhydroxy polyester solution was added 279.3 g ofisocyanatoethyl methacrylate (IEM, 1.8 moles 90% of the theoreticalamount required to react with all of the hydroxyl group) 186 g butylacetate, and 0.34 ml dibutyltin dilaurate (DBTDL, available from AlphaChemical Company).

Stirring and maintaining a dry air flow through this solution wasre-established and it was brought to 70° C. After about 12 hours, thesolution was monitored for the presence of free isocyanate by infraredspectroscopy; heating was continued until isocyanate functionality wasabsent (12 to 16 hours). On cooling, there was obtained an approximately60% solution of an ethylenically unsaturated polyester of this inventionhaving a calculated ethylenic equivalent weight of 245.

A portion of the solution obtained was diluted to 20% solids by weightand 7.0% by weight (based on solids) of "Irgacure" 184 (a photoinitiatoravailable from Ciba Geigy Co.) was added and mixed until dissolved. Theresulting mixture was coated onto polyester film using a No. 50wirewound bar coater. The coated samples were air dried for about 18hours at room temperature (about 25° C.). The samples were cured bypassing twice through a RPC UV Processor, Model No. QC 1202(manufactured by PPG Industries, Inc.). The processor had two 300watts/inch (120 watts/centimeter) lamps and was operated at a belt speedof 9.1 meters/minute. Clear, colorless, cured (crosslinked) coatingswere obtained. This coating was solvent resistant for at least 6 hoursto amyl acetate, acetone, 95% ethanol, 50% ethanol, water, and 5%aqueous ammonia. The haze value was 4.2% and no print-through wasobserved after the hot cup print test.

EXAMPLES 2-11 AND COMPARATIVE EXAMPLE 1

Solutions of ethylenically unsaturated polyester of this invention wereprepared, coated onto polyester film and cured as described in Example 1with the exception that only 4% "Irgacure" 184 was used and the ratiosof diepoxide, itaconic acid and acrylic acid and percent of thetheoretical amount of isocyanatoethyl methacrylate required to reactwith the hydroxyls present in the polyhydroxy polyester are as shown inTable I. Clear colorless coatings that were as abrasion, heat andsolvent resistant as the coatings of Example 1 were obtained in Examples2-11. Table I also shows the calculated molecular weight and calculatedethylenic unsaturated equivalent weight as well as the haze found foreach polyester. Comparative Example 1 was prepared as in Example 1 usingdiepoxide, itaconic acid, and acrylic acid, but omitting the addition ofisocyanatoethyl methacrylate.

                  TABLE I                                                         ______________________________________                                              MOLE RATIO                                                              EX.    OF REACTANTS    CALCULATED    HAZE                                     NO.   D/I/A.sup.(a)                                                                           IEM.sup.(b) (%).sup.(c)                                                                  MW.sup.(d)                                                                            EUE.sup.(e)                                                                         %                                    ______________________________________                                        1     4/3/2     7.2(90)    3010    245   4.2                                  2     4/3/2     4.8(60)    2640    270   5.5                                  3     4/3/2     2.4(30)    2265    305   5.5                                  4     2/1/2     3.6(90)    1510    230   4.7                                  5     2/1/2     2.4(60)    1325    245   4.7                                  6     2/1/2     1.2(30)    1140    270   5.4                                  7     2/1/2.sup.(f)                                                                           3.6(90)    1540    235   5.6                                  8     5/4/2     9.0(90)    3760    250   4.3                                  9     10/9/2     18(90)    7505    260   4.4                                  10    40/39/2    72(90)    19,200  265   4.5                                  11    1/1/0     1.8(90)    30,000.sup.(g)                                                                        270   4.1                                  Comp. 4/3/2     0(0)       1890    380   7.0                                  ______________________________________                                         .sup.(a) Ratio: diglycidyl ether of bisphenol A/itaconic acid/acrylic aci     .sup.(b) IEM is isocyanatoethyl methacrylate                                  .sup.(c) Percent of theoretically available hydroxyl groups                   .sup.(d) Number average molecular weight                                      .sup.(e) Ethylenic unsaturation equivalent weight                             .sup.(f) Methacrylic acid used in place of acrylic acid                       .sup.(g) Degree of polymerization: n˜60                            

It is to be observed in Table I that cured coatings prepared from 2/1/2to 40/39/2 diepoxide/itaconic acid/acrylic acid and 30 to 90% of thetheoretical amount of isocyanatoethyl methacrylate are abrasionresistant having an abrasion resistance as expressed by haze valueslower than 6.5% and as low as 4.2%. A cured coating when prepared from1/1 diepoxide/itaconic acid even without acrylic acid had an abrasiveresistance as expressed by haze value of 4.1%. The samples showedexcellent solvent resistance and heat resistance because no effect onthe samples of Examples 1-11 and Comparative Example 1 could be observedafter contacting the coatings for at least 6 hours with amyl acetate,acetone, 95% ethanol, 50% ethanol, water, or 5% aqueous ammonia, orafter subjecting the samples to the hot cup print test. The coating ofComparative Example 1, having an ethylenic unsaturation equivalentweight of 380, exhibited a haze value of 7.0 which haze value is abovethe desired haze value.

EXAMPLES 12-13 AND COMPARATIVE EXAMPLES 2-5

Solutions of ethylenically-unsaturated polyester were prepared, coatedonto polyester film, and cured by the procedures described in Example 1using the reactants shown in Table II. The cured coatings of theinvention in Examples 12 and 13 were clear, colorless coatings and wereabrasion resistant as shown by the haze values in Table II, were heatresistant exhibiting no print-through after the hot cup print test, andwere solvent resistant, being unaffected by exposure to amyl acetate,acetone, 95% ethanol, 50% ethanol water, or 5% aqueous ammonia for 6hours. The cured coatings of Comparative Examples 2-5 did not exhibitacceptable abrasion resistance, but were resistant to heat and solvents.

                  TABLE II                                                        ______________________________________                                              MOLE RATIO                                                              EX.   OF REACTANTS     CALCULATED    HAZE                                     NO.   D/S/A.sup.(a)                                                                           IEM.sup.(b) (%).sup.(c)                                                                  MW.sup.(d)                                                                            EUE.sup.(e)                                                                         (%)                                  ______________________________________                                        12    2/1/2     3.6(90)    1500    270   4.5                                  13    4/3/2     7.2(90)    2975    325   6.5                                  Comp  4/3/2     4.8(60)    2600    380   7.5                                  Comp  4/3/2     2.4(3)     2230    505   10.5                                 3                                                                             Comp  4/3/2     0(0)       1860    930   26                                   4                                                                             Comp  1/1/0     1.8(90)    30,000.sup.(f)                                                                        410   7.5                                  5                                                                             ______________________________________                                         .sup.(a) Ratio: diglycidyl ether of bisphenol A/succinic acid/acrylic aci     .sup.(b) IEM is 2isocyanatoethyl methacrylate                                 .sup.(c) Percent of theoretically available hydroxyl groups                   .sup.(d) Number average molecular weight                                      .sup.(e) Ethylenicunsaturation equivalent weight                              .sup.(f) Degree of polymerization: n˜65                            

In Table II, it can be observed that the cured coatings of polyesterscontaining a calculated ethylenic unsaturation equivalent weight (EUE)of less than 330 have excellent abrasion resistance, vis., a haze valueof no more than 6.5, whereas the comparative cured coatings preparedfrom polyesters having an equivalent weight of above 330, have inferiorabrasion resistance.

EXAMPLE 14

The procedure of Examples 2-11 was repeated to prepare another polyesterof this invention using in place of the aromatic diepoxide 280 g of thecycloaliphatic diepoxide ERL™ 4221 (3,4-epoxy-cyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, epoxy equivalent weight 140, available fromUnion Carbide Corp.). The polyester obtained had a ratio of 4 molescycloaliphatic diepoxide: 3 moles of itaconic acid: 2 moles of acrylicacid with 90% of the hydroxyls reacted with IEM. The ethylenicallyunsaturated polyester obtained had a calculated molecular weight of 2660and equivalent weight of 220 per ethylenic double bond. Coatingsprepared and cured as described in Examples 2-11 were colorless,abrasion and heat resistant, and were uneffected by contact with amylacetate, acetone, 95% ethanol, 50% ethanol, water, and 5% aqueousammonia for 6 hours.

EXAMPLE 15

The procedure of Examples 2-11 was repeated to prepare another polyesterof the invention using 48.8 g itaconic acid (0.375 moles) and 62.30 gphthalic acid (0.375 moles) in place of 0.75 mole itaconic acid. Thepolyester obtained had a ratio of 4 moles of diepoxide: 3 moles ofdicarboxylic acid: 2 moles of acrylic acid with 90% of the hydroxylsreacted with isocyanatoethyl methacrylate. The ethylenically unsaturatedpolyester obtained had a calculated molecular weight of 3065 and an EUEof 285. Coatings prepared and cured as described in Examples 2-11 werecolorless and abrasion and heat resistant. No effect on the curedcoatings could be observed after they had been contacted for at least 6hours by amyl acetate, acetone, 95% ethanol, 50% ethanol, water, or 5%aqueous ammonia.

EXAMPLE 16

The procedure of Example 1 was repeated to prepare another polyester ofthe invention using 30 g acetic acid (0.5 mole) in place of 0.5 mole ofacrylic acid. The ethylenically unsaturated polyester obtained had acalculated molecular weight of 2985 and an EUE of 293. A coatingprepared and cured as described in Example 1 was colorless, abrasion,heat, and solvent resistant.

When Example 16 was repeated using 0.5 mole of hexanoic acid, theethylenically unsaturated polyester had a calculated molecular weight of3100 and an EUE of 305. Coatings similar to those of Example 16 areobtained.

Various modifications and alterations of this invention will becomeapparent to those skilled in the art without departing from the scopeand spirit of this invention.

It is claimed:
 1. Ethylenically unsaturated polyester comprising thereaction product of (a) a polyhydroxy polyester which is the addition orcondensation product of a saturated or unsaturated dicarboxylic acid andan acyclic or carboxylic organic diepoxide, with (b) polymerizableethylenically unsaturated compound having a functional group reactivewith the hydroxyl groups of the polyhydroxy polyester, saidethylenically unsaturated polyesters having an equivalent weight of lessthan about 330 per ethylenic groups.
 2. The polyesters of claim 1further comprising monocarboxylic acid and/or monoepoxide.
 3. Theethylenically unsaturated polyesters of claim 1 represented by theformula ##STR24## wherein each R¹ and R² is independently a divalentorganic group having 2 to 40 carbon atoms selected from saturated orunsaturated straight or branched aliphatic or cycloaliphatic groups oraromatic groups,each R³ is independently hydrogen or an alkylene grouphaving 2 or 3 carbon atoms that together with atoms in R¹ and the--CH--CH-- group to which it is bonded form a 5- or 6-membered trivalentcycloalkane group; ##STR25## in which R is hydrogen or a methyl group;R⁷ is a monovalent organic radical having 1 to 24 carbon atoms and isselected from saturated or unsaturated straight or branched chainaliphatic groups and aromatic groups; R⁸ is an alkylene group having 2to 12 carbon atoms; and R⁹ is a divalent organic group selected fromlinear branched, and cyclic alkylene groups having 2 to 20 carbon atoms,phenylene groups, naphthylene groups, and phenylenemethylenephenylenegroups, the organic group optionally substituted by up to four loweralkyl groups having 1 to 4 carbon atoms; R¹⁰ is hydrogen or an alkylgroup having 1 to 4 carbon atoms; and R⁵ is selected from ##STR26##where R¹, R³, and R⁴ are as defined above and R¹² is a monovalentorganic radical having 1 to 20 carbon atoms and is selected fromsaturated and unsaturated straight or branched chain aliphatic groups oraromatic groups; R⁶ is selected from R¹¹ and ##STR27## where R¹, R³, R⁴,R⁷ and R¹¹ are as defined above; n is a number having an average valueof 1 to 100, except where R⁵ is ##STR28## n may be a number having anaverage value of 0 to
 100. 4. The ethylenically unsaturated polyestersof claim 2 wherein the polyhydroxy polyester is the reaction product ofn+1 moles of diepoxide, n moles of dicarboxylic acid, and 2 moles ofmonocarboxylic acid in which n is a number having a value of 1 to 100.5. The ethylenically unsaturated polyester of claim 3 having the formula##STR29## wherein each R¹ and R² is independently a divalent organicgroup having 2 to 40 carbon atoms selected from saturated or unsaturatedstraight or branched aliphatic or cycloaliphatic groups or aromaticgroups, with the proviso that R¹ contains no heterocyclic groups;each R³is independently hydrogen or an alkylene group having 2 or 3 carbon atomthat together with atoms in R¹ and the --CH--CH-- group to which it isbonded form a 5- or 6-membered trivalent cycloalkane group; each R⁴ isindependently ##STR30## in which R is --H or --CB₃ ; R⁷ is a monovalentorganic radical having 1 to 24 carbon atoms and is selected fromsaturated or unsaturated straight or branched chain aliphatic groups andaromatic groups; R⁸ is an alkylene group having 2 to 12 carbon atoms;and R⁹ is a divalent organic group selected from linear, branched, andcyclic alkylene groups having 2 to 40 carbon atoms, naphthylene groupsand phenylenemethylenephenylene groups, the organic group optionallysubstituted by up to four lower alkyl groups having 1 to 4 carbon atoms;and n is a number having a value of 1 to 100 sufficient to provide tothe ethylenically-unsaturated polyester a number average molecularweight of 500 to 30,000.
 6. The polyester of claim 4 in which n has avalue of 1 to
 10. 7. The polyesters of claim 2 wherein the dicarboxylicacid is itaconic acid, the monocarboxylic acid is acrylic acid, thediepoxide is a diglycicyl ether of bisphenol A, and the ethylenicallyunsaturated compound is isocyanatoethyl methacrylate.
 8. Anethylenically unsaturated polyester comprising the addition product of(1) the reaction product of 3 moles itaconic acid, 2 moles acrylic acid,and 4 moles of the diglycidyl ether of bisphenol A, and (2) 2.4 to 7.2moles isocyanatoethyl methacrylate.
 9. The process of preparingethylenically unsaturated polyesters comprising the steps of(1)preparing a polyhydroxy polyester by reacting n moles of organicdicarboxylic acid, 2 moles of a saturated or unsaturated monocarboxylicacid, and n+1 moles of diepoxide, where n is 1 to 100, and (2) heatingthe polyhydroxy polyester of step (1) with sufficient polymerizableethylenically-unsaturated compound having a functional group reactivewith hydroxyl groups sufficient to provide to the polyester anequivalent weight of less than about 330 per ethylenic groups.
 10. Theprocess according to claim 9 wherein n has a value of 1 to
 10. 11. Theprocess according to claim 9 wherein the polyhydroxy polyester isprepared by reacting 4 moles of diepoxide, 3 moles of dicarboxylic acid,and 2 moles of monocarboxylic acid.
 12. Coating composition comprising asolution of the ethylenically-unsaturated polyester as defined in claim1 in an organic solvent.
 13. The process of curing a composition asdefined in claim 1 to a solvent, stain, heat, and abrasion resistantstate comprising exposing the composition in the form of a coating on asubstrate to effective activating energy.
 14. Substrate having a curedcoating of the polyester of claim
 1. 15. Ethylenically unsaturatedpolyester comprising the reaction product (a) a polyhydroxy polyesterwhich is the addition or condensation product of a saturated orunsaturated dicarboxylic acid that is aliphatic, cycloaliphatic, oraromatic and can be substituted by a non-interferring group and anorganic diepoxide having a molecular weight of up to about 1000 that isbranched or straight chain aliphatic, cycloaliphatic, or aromatic andcan be substituted by a non-interfering group, with (b) polymerizableethylenically unsaturated compound selected from acrylic and methacrylichalides, anhydrides, and isocyanates, N-methylolacrylamide,N-alkoxymethylacrylamide, and ethenyl and isopropenyl azlactones, saidethylenically unsaturated polyesters having an equivalent weight of lessthan about 330 per ethylenic groups and a number average molecularweight of 500 to 30,000.
 16. The polyesters of claim 15 further reactedwith a monocarboxylic acid that is aliphatic, cycloaliphatic, oraromatic and can be substituted by a non-interfering group, and/ormonoepoxide that is saturated or unsaturated aliphatic, cycloaliphaticor aromatic and can be substituted with non-interferring groups and cancontain catenary --O--, ##STR31## and --SO₂ -- groups.